Use our Body Fat Calculator to estimate your body fat percentage quickly and reliably using the U.S. Navy method. Enter your height, neck, waist, and (for women) hip measurements, along with your body weight, to see your estimated body fat %, fat mass, and lean mass. This simple tool helps you track progress, set realistic goals, and understand your current fitness level.
How the Body Fat Calculator works
The Body Fat Calculator applies the U.S. Navy circumference method, a research-backed approach that estimates body fat by combining height with key body circumference measurements. For men, the calculation uses neck and waist. For women, it uses neck, waist, and hips. These locations correlate with typical fat distribution patterns, allowing the formula to produce a close approximation of total body fat percentage without specialized equipment.
After calculating your body fat percentage, the calculator multiplies it by your body weight to estimate fat mass (the weight of all fat in your body) and lean mass (everything else, including muscle, bone, and water). Because these results use the units you provide, you can work entirely in metric (cm, kg) or imperial (in, lb) without converting units yourself.
What you need to measure
- Height: Barefoot, standing tall against a wall.
- Neck: Below the Adam’s apple, where the neck is narrowest.
- Waist: Around the navel (belly button) level, relaxed and not sucked in.
- Hips (women): At the fullest part of the buttocks.
- Body weight: Ideally measured in the morning after using the restroom.
Why body fat percentage matters
Body fat percentage is a more informative indicator of fitness than weight alone because it distinguishes fat mass from lean mass. Two people can weigh the same but have very different health and performance profiles due to differences in body composition. Monitoring body fat percentage can help you refine calorie targets, adjust training programs, and evaluate whether you are losing fat, gaining muscle, or both.
Healthy body fat ranges
While optimal ranges vary by age and genetics, common reference ranges are:
- Men: Essential fat (2–5%), Athletes (6–13%), Fitness (14–17%), Average (18–24%), Obese (25%+)
- Women: Essential fat (10–13%), Athletes (14–20%), Fitness (21–24%), Average (25–31%), Obese (32%+)
These categories are guidelines, not medical diagnoses. Consider consulting a healthcare provider for personalized advice.
How to take accurate measurements
- Use a flexible tape measure and take measurements in front of a mirror or with a helper.
- Keep the tape snug but not tight; avoid compressing the skin.
- Measure at the same time of day, ideally in the morning before eating.
- Repeat each measurement 2–3 times and use the average for consistency.
- Log your results weekly or biweekly to track trends rather than daily fluctuations.
Understanding your results
Your body fat percentage provides a snapshot of your current composition. Fat mass is calculated by multiplying your weight by the body fat percentage, while lean mass is the remainder. If your goal is fat loss, pair a modest calorie deficit with resistance training and adequate protein to preserve lean mass. If you’re aiming to gain muscle, a slight calorie surplus, progressive strength training, and sufficient recovery can support lean mass gains without excessive fat gain.
Limitations of the method
- Individual variation: Body shape and fat distribution differ across individuals.
- Measurement error: Small mistakes with the tape can shift results by 1–3%.
- Hydration and timing: Bloating or water retention can alter waist and hip readings.
- Comparisons: For clinical decisions, consider additional methods like DEXA or a professional assessment.
Tips for better progress tracking
- Combine the Body Fat Calculator with progress photos, tape measurements, and performance metrics.
- Track averages over several weeks to see true trends.
- Adjust calories and training gradually; large swings often backfire.
- Celebrate non-scale victories like improved strength, sleep, and energy.
Use this Body Fat Calculator regularly to measure what matters, make data-driven adjustments, and stay motivated on your health and fitness journey.